Does sonar spook fish?

[J.A. Veil]

I am aware that some anglers believe that sonar pings can disturb and spook fish. They claim to turn off their fishfinders when actively working on fish. Others leave the sonar on at all times. I tend to fall in the latter group, although it is primarily just my habit to do that. I don't have any strong evidence one way or the other.

I thought I would start a thread for others to add their opinions. For those of you who believe that sonar spooks fish, at what point do you turn off the sonar?

[manlystanley]

Interesting topic. I'm going to follow it.

[ronaultmtd]

Never seen any evidence that today's technology has any effects on fish...this is not the old WWII sonar technology- I have caught redfish in two feet of water with my Lowrance Elite 5 DSI on...and speckled trout- so if it doesn't stop them from biting in that shallow water...what does that say?

[D3NAL1]

Its one of those things that best works for you, i suppose. FF on or off is like comparing with or without flouro leader. The only person ive ever heard suggest turning off your FF is Shawn Kimbro

[DanMarino]

I would think that in heavily pressured areas, the sonar pings just become background noise to the fish. My guess is that in remote/undisturbed areas, sonar and motor noise might be a bigger deal since the fish aren't used to whatever noise is generated. I've caught plenty of fish with the sonar unit going. I typically leave my sonar unit at home when I fish Mattawoman, Mallows, or the Upper Potomac river.

[dasher]

Shawn is who I heard that from as well. But he cited a study where it was very clear that fish avoided the area where the cone of pings traversed. Anecdotal evidence of catching or not catching while using a FF are not really evidenced based. There can be other factors.

[Mark]

This is a frequent topic of discussion among bass anglers.

I've read in various articles and in on-line discussion groups that FF pings are beyond the frequency range heard by fish.

Others say that there is so much noise underneath the water (remember that sound travels faster underwater than through the air) that pings even if heard are not disruptive. They're just part of a cacophony of sound that underwater creatures live with.

I notice no difference with my FF on.

I believe far more disruptive noise is generated by our Mirage Drives, Propels, paddles or even by dropping our pliers to the deck.

[ronaultmtd]

I'm with you Mark- drop a sinker in an aluminum boat...or scuff your feet...boat noise spooks more fish than anything else- hull slap, engine noise, banging gear around, or talking, listening to music...sonar...maybe- if you are in a pristine area that humans have never touched...I notice that when I start catching fish trolling in my Hobie and the charter boats see me land a few fish- they come over and troll on top of me and the fish stop hitting- I think it is the propeller noise that they spook from...

[J.A. Veil]

As others have noted, Shawn Kimbro seems to be a leading proponent for turning off sonar in shallow water. I posted a similar question on the Technical Fisherman fishing board. There were a range of replies (most suggesting that they did not think sonar made a difference). Shawn replied there saying:

"Sorry, to disagree, but shallow water is the last place I would use sonar. I doubt you're going to see a stump on your fish finder before you hit it and you're a lot more likely to spook fish when you're in shallow water. I use my fish finder when I'm searching ledges and in open water, but if I know I'm going to cast at a bridge piling, or drift along a bank, or cast in from outside a warm water discharge, I kill it. This isn't anything I came up with, it's a very well-known tactic used by fresh-water bass fishermen and tournament pros. I've personally witnessed fish spook by fish finders and I've heard Lenny Rudow talk about experiments he has done in large aquariums when fish noticed the pings. Keep in mind that sensing sound and movement is one of a striper's superpowers. They see about like we do but they can hear noise and sense sound a lot better, maybe a hundred times better. I believe that any unnatural noise can put fish on alert, especially the big ones. IfI you're happy with the way you are catching, I wouldn't change a thing, but when things are tough, or you are consistently catching smaller fish, why not experiment and give yourself every advantage you can?"

When trolling from my kayak in shallow water I find it very important to know what the depth is so I don't get too shallow (dragging bottom) or too deep for my target depth. Turning off the sonar would be counterproductive for me. And as others have correctly noted, there are other sources of noise when pedaling, paddling, or shifting weight in the kayak.


I can see some value to turning off the sonar when casting to stump fields or other shallow areas from my center console. When I am using my outboard, I do worry about hitting stumps and damaging the prop. When I am using my trolling motor, I am less concerned. I will try some experiments this summer in those shallow areas -- for example, 20 mins without the sonar followed by 20 mins with the sonar -- to see if I find any difference.

[dhawk]

I leave mine on in large bodies of water like the bay and tidal creeks but if I'm fishing a small pond or an area that doesn,t get a lot of boat traffic like say a tidal marsh where only kayak can get I will keep it off or not bring it at all.If I know and area well and am not trying to hold a certain depth i will also keep it off. Don't know if it make a difference or if its just in my head but that's what I do.

[kevinfry]

Well, as noted I don't see how you could troll shallow or an edge consistently without the FF.
As for the research, I'd like to see a well designed study. Noting the behavior of fish inside the cone does not seem relevant to me in shallow water? Who fishes under the boat in less that six ft of water? I also wonder why a FF is so effective ice fishing if this is a problem. Those guys are definitely fishing in a noise rich cone and are.not able to cast outside of it

Sent from my SM-G360V using Tapatalk

[D3NAL1]

I tested this out this morning. With ff on and off. No difference. At least i knew where the fish were. Caught all mid to high 20s
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[Jimbo]

I spoke to a very wary striped bass last night and he put this quandary to rest once and for all. He said, and I quote, "uh, nope, never noticed it".

So there you have it.

[dasher]

Most of do not spend the same quantity or quality time on the water as some guides. I would think that if Shawn thinks sonar spooks fish, he is probably right. If Lenny thinks it, it is probably so. If we catch fish there is no reason to do anything different. But, there may be benefit in giving experts the benefit of the doubt & listening to what they say.

All that said, if I'm noisy in my boat it likely doesn't matter.

[Huntrava]

I suspect there are easier ways to gain efficiencies rather than turning off one of your most valuable tools. You've probably lost 10 fish due to being noisy for every one fish you might have lost due to sonar.